Method of treating wood for protecting the same from bluing



pose.

Patented July 3,

messes nm'rnon or TREATING woon son rim-- "momma 'mn slum:v mom ammo John Tobias Olsaon, Bollnas, Sweden, assignor to Stockholm Superfosfat Fabrlks Aktiebolag, Stockholm, Sweden, a corporation of Sweden No Drawing. Appllca gel-Ina! No. 574,044.

tion' November 9, ,1931, In Sweden September 16,

z Olaims. (01. 99-12),

The surfaces of sawn wood, especially at hot and damp weather, become blue-coloured during the drying ofthe wood which is caused by a number of microorganisms which rapidly grow on the-surfaces of the wood as long as the temperature and the decree of moisture in e wood are favourable therefor. On' account of e blue spots appearing on the surfaces of the wood the quality of the latter and also its'value and usefulness for several purposes are reduced. The blu-* ing or "blue'surfacef appearing yearly on sawn, wood consequently means a national economic loss which is especially severe in case of wood to e be exported.

1s The microorganisms causing the bluing are generally spread as spores, which stick to the surfaces of the wood where they, as long as the temperature and degreeof moisture are favourable,

- develop themselves and grow rapidly. During an (1171M of freshsawn wood its content of moisture will gradually be lower than that which is necessary for the development of said Therefore, by applying to the surfaces of the wood it will be possible to prevent such development during the periodrequired fordecreasing the content'ofmoistureofthewoodtosuchalimit below which the development of. said microorgan'ismscannot take place. Several antiseptic gsuhstanceshavebeenproposedandusedinpractiee for said purpose. It has for instance been propoeedtotreatthewoodwithamixtureof stances has a powerful antiseptic action. The

menteltheinquestiomthanif 'linglc'mbstancewwldbeusedforsaidpurlheuseof' aneee salts has, however, also thatthewoodsurfacesaiterhavbeeomecolom'edbrown. Thiscol no doubt feeble but distinctly Xoreovensaid substances are somewimtirritatmsfortheskinwhichisdisasree- "able for the workmen who are occupied with The preemtinvention has for its object a methodfor preventing thebluing viz. the formass tl9nofbluestu;taces"onthewoodwhichoflers 'servative action obtained by "an aqueous. solution the advantages that said drawbacks are removed and that the agent used is -two or three times as efllcacious as the above 'mentioned agent previously proposed. The present method consists in this that the new-sawn wood is dipped or submerged into an aqueous solution containing soluble salts or boron and chlorophenols, or that such solution is sprayed onto the surfaces of the wood or applied thereon .in any other way. Investigations have proved that the soluble alkali salts of a boron, for instance the sodium salt of tetraboric acid (borax), the sodium salt of metaboricacid and others have a very good capacity of preventing the development on the surfaces of wood of "bluing microorganisms" and that this capacity can be utilized by applying a solution'of said salts I of the boric acid to the surfaces of the wood, for instance by dipping the wood into a solution of said salts. The action of said salts of the boric acid is, however, considerably increased if \the 7 solution also contains chlorophenols, preferably chloro-meta-cresol. The simultaneous action of said substances has been found to be more eillcacious than the action of each substance used separately in a corresponding quantity. It is therefore'suillcient that the solution is in contact with the wood surfaces for a relatively short time. The pure chlorophenols are rather sparingly soluble in water. By the addition of alkali salts of the boric acid the solubility of the chlorophenols is considerably increased due to the formotion of complex salts when' the two constituents are at the same time disolved water. This combination of, two substances each of which has an antiseptic action, has for its object to execute a more universal action on the different species of the microorganisms causing "blue surface" on the wood, and whose individual resistance is diiferent. Due to the efllcacious precontaining salts of boric acid as well as chlorophenols the solution may be wed in a highly diluted state and has no irritating action on the skin of the workmen and iinally it does not at all colour thesurface of the treated wood.

'Iclaim:

1. The method of treating wood for protecting the same from bluing, conslstlng in exposing the surfaces 0! freshsawn wood to the action of an aqueous solution containing borax and chlorometa-cresol. 2. An agent for protecting wood from bluing, of an aqueous solution of borax and chloro-meta-cresol.

JOHN TOBIAB OLSSON. n 

